Suspended arch for furnaces



Feb. 24, L. L. LADD SUSPENDED ARCH FOR FURNACES Filed Dec. 6, 1940 5 Sheets-Sheet l Him...

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Feb. 24, 1942. L. LADD 2,274,240

SUSPENDED ARCH FdR FURNACES Filed Dec. 6, 1940 5 Sheets-Sheet 5 J r INVENTOR. [6666* L. Lacie! Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE SUSPENDED FURNACES Lester L. Ladd, Lockport, Ill.

Application December 6, 1940, serial No. 368,765

' ,6 Claims. (01. 110-99) This invention relates to suspended arches for furnaces, being intended mainly, although not exclusively, for use in the construction of tunnel kilns for the baking and glazing of ceramic products.

I A known form of suspended arch or roof for such kilns consists of laterally spaced steel 1- beams or girders that span the top of the tunnel and are supported at their ends on the side walls, and rectangular fire-brick blocks with slotted top walls that embrace and hang from the lower flanges of the I-beams. A row of these blocks is suspended from each beam, and the transverse dimensions of the block are such that they are substantially in edge to edge contact with each other both lengthwise and crosswise of the tunnel. This construction has several faults, which it is the main object of this improvement to overcome. For one thing, hot air and gases, of course, rise, and much of such air and gases escapes upwardly through the cracks or joints between adjacent blocks. Again, fire-brick is far from the best and most efiicient of the known heat insulators; and, since the entire surface of the arch exposed to the heat in the tunnel is of fire-brick, considerable heat is lost by radiation from the top of the arch.

Again, the known construction is not applicable to what are known as circular kilns, becausein the latter the beams or girders that span the top of the tunnel are not parallel, but, being disvention, as applied toboth straight and circular kilns, are shown in in which- Fig. 1 is a fragmentary plane view of the arch or roof of a circular kiln embodying the present invention.

Fig. 2 is a transverse vertical section, taken on the line 22 of Fig. 1.

Fig. 3 is a longitudinal vertical section, taken on the line 3-3 of Fig. 1; this view also showing the insulating powder spread on the arch slabs between adjacent slab hangers.

Fig. 4 is a view similar to Fig, 1, showing a modified form of slab hanger and structural steel suspension member therefor.

Fig. 5 is a view similar toFig. 2, taken on the line 5-5 of Fi 4-.

Fig. 6 is 'a view similar to Fig. 3, taken on the line 6-6 of Fig. 4 1

the accompanying drawings,

Fig. 7 is a View similar to Fig. 2, showing a modified form of the invention used for stepping up the arch from the sides to the center of the tunnel.

Fig. 8 is a view similar to Fig. 7, but showing and II designate outer and inner masonry side walls of an annular tunnel [2 through which the ware to be treated is moved by a slow conveyor (not shown). Extending across the top of the tunnel l2, and supported at their ends on ledges I0 and II of the walls l0 and l I are laterally spaced I-beams l 3. As will be seen from Fig.1, these beams 13 are not parallel, but, being disposed radially of the kiln, diverge slightly from their inner to their outer ends.

Suspended from the beams I3 are fire-brick hangers I4. Preferably, and as herein shown, these hangers H are formed with undercut slots H5 in their upper portions that embrace substantially the lower halves of the I-beams l3, in the manner clearly shown in Fig. 3, by which they are easily applied to the beams by a mere sliding operation and by which they are suspended from the lower flanges of the beams. Incidentally, it

may be noted that the slots l5 are wider than the parts of the beams which they embrace, so that all of each beam except its lower flange is exposed to air, facilitating the radiation of heat from the beam and preventing deformation or possible destruction of the beam from the high heat in the tunnel I2.

As will be seen from Fig. .2, the hangers II are disposed in side to side contact with each other throughout the full width of the tunnel l2.

On the lower ends of the hangers M are ,formed integral horizontal shoulders l6; and reportions of the slabs rest on the shoulders I6 in edge toedge contact with each other; and preferably, as shown in Fig. 2, the upper and lower halves of the contact joints are relatively offset, which is accomplished by providing on the meeting edges contiguous overlapping edge portions I8 and I9, each preferably of one half the thickness of the slab. This construction provides between adjacent slabs a joint less permeable to the hot air and gases in the tunnel than would be a single flat'surface joint. The described contact of the other opposed edges of the slabs with the hangers also creates a similar rectangular joint that seals the roof against the escape of hot air and gases better than would a plain flat surface contact.

The structure as thus far described is complete, as an improved arch or roof for a kiln tunnel'or other furnace; but preferably I add thereto a heat insulating feature which I have found in practice to be very effective, and to substantially reduce the expense of operating the kiln. This consists in the application to the tops of the slabs ll of layers or piles 20 of a material that possesses a greater heat insulating value than the fire-brick itself. An excellent material for this'purpose is a powder known as diatomaceous earth, another name for which is kieselguhr, the source of which is the accumulated deposit of the silicious cell walls of diatoms. Such insulating material is so applied, as shown in Fig. 3, that it is entirely out of contact with the beams I3, so that it does not interfere with the radiation of heat from said beams. It does, however, effectively seal the joints between the slabs l1, and it also very substantially increases the heat confining capacityof the entire arch or roof.

The above described structure may also be employed as an arch or roof for a straight or rectilinear kiln tunnel, such as is illustrated in Figs. 4, 5 and '6, with the sole exception that in the latter case the slabs may be made rectangular and of uniform size. In Figs, 4, 5 and 6, however, I have illustrated modified forms of beams and hangers. In this modified form, each structural steel beam consists of a pair of parallel inwardly facing channels 2|; and the hangers 22, which are somewhat longer and narrower than the hangers H, are formed on their upper ends with heads 23 that are entered by a sliding movement-between the channels 2| and rest on I the lower flanges of the latter, as clearly shown in Fig. 6. Tie bolts 23' connect the two channels at their ends and serve to securely'clamp the chanels on the heads 23 of the hangers. The removable slabs ll' are, as above stated, of uni: form ,size and rectangular form. Two opposed edges of these slabs. rest on shoulders IS on the lower ends of the hangers 22, these shoulders being identical with the shoulders "5 shown in Fig. 3. The other opposed edges of the slabs ll .meet in overlapping joints, identical with those shown in Fig. 2,. The somewhat greater length of the hangers 22, when the latter are suspended from the twin channel beams shown in Figs. 4, 5 and 6, permits the slab IT to be readily removed between adjacent hangers by simply tilting one edge of the slab upwardly and then withdrawing it from the top. Since the I-beams l3 of Figs. 1, 2 and 3 do not present any interference with the removal of the slabs H, the

- hangers H in that case may be made shorter, as

shown. Layers or piles 20 of the same high value insulating material are spread on the slabs H, as shown in Fig. 6; the greater length of the embodying the structural principle and details of the structures above described, and show how this principle and these details may be embodied in what is known as a stepped-up arch or roof. This is simply a roof which is highest above the median line of the tunnel and slopes downwardly more or less gradually to the side walls or edges of the tunnel. In Fig. 7 I show the I-beams l3,

hangers I4 and slabs I! of Figs. 1, .2 and 3; and

in Fig. 8 I show the twin channel beams 2|, hangers 22 and slabs ll of Figs. 4, 5 and 6. The only change required to create this stepped-up form of arch or roof is to mount thebeams at gradually increasing heights from the sides to the median line of the tunnel, and to relatively step-up the slab supporting shoulders 16 on opposite sides of the intermediate hangers 22 so as to create a stepped effect of the slabs supported on said shoulders. A circular kiln having a curved arch or roof. of this general character is shown in my former Patents No. 1,903,118, March 28, 1933'and No. 2,127,742, August 23, 1938, the purpose of which, as illustrated in Figs. 5 and 6 of the latter patent, being to enable a car or truck traveling through the tunnel to be piled up higher at the middle than at the sides with the wares to be baked, annealed or otherwise treated in the kiln. Figs. 7 and 8 herein show how tunnel roofs or arches of the curved or crown type disclosed in the aforesaid patents may be built, under the principle and with the structural elements, of this invention.

Among the practical advantages of this invention may be mentioned the following:

The hangers and slabs are easily replaceable when required. This is particularly advantageous in kilns used for glazing sewer pipes and other articles requiring a glazed surface, wherein the products used to effect the glazing also attack and eat into the fire brick blocks of the roof or arch, requiring frequent renewals.

It will be observed that the beam supports of the hangers are neither wholly nor partiallyburied in the insulating powder on top'of the slabs, but are freely exposed to the air above the roof so that they can readily radiate their heat and are thus saved from deformation or destruction by the intense heat of the kiln or other furnace.

The described construction makes practical the use of slabs of trapezoidal form in circular kilns or other furnaces, where the rectangular slabs used in straight or rectilinear kilns obviously could not be used.

The described construction, by reason of the use of the diatomaceous earth or other material of higher heat insulating value than fire brick on top of the slabs, effects a substantial economy of heat, and consequent reduction of expense in operating the kiln.

I claim:

1. A suspended arch for furnaces, comprising, in combination, laterally spaced beams having horizontal flanges on their lower edges, said beams spanning the top of the furnace and supported at their ends on the side walls of the furnace, laterally spaced rows of fire brick hangers formed on their upper ends with shoulders by which they are slidably suspended on said beam flanges and on their lower ends with slabsupporting shoulders, the hangers of each row in combination, laterally spaced I-beams spanning the top of the furnace and supported at their ends on the side walls of the furnace, lat: erally spaced rows. of fire brick hangers formed with undercut slots in their upper portions embracing the webs and lower flanges of said I- beams, said slots forming shoulders by which said hangers are slidably suspended from said lower flanges, said hangers having on their lower ends outwardly extending slab-supporting shoulders, the hangers'of each row being disposed in side to side'contact with each other, and flat fire brick slabs supported at opposite edges thereof on adjacent lower shoulders of adjacent rows of said hangers, the slabs of each row being in edge to edge contact with each other, and each of said slabs' being independently removable by a vertical movement through the space between its supporting hangers. Y

3. An embodiment of the subject-matter defined in claim 2, wherein the walls of the slots in the hangers are wide enough to be out of contact with the webs of the I-beams, whereby to permit access of air to said webs to prevent overheating of said beams.

4 A suspended arch for furnaces, comprising,

in combination, laterally spaced beams spanning the top of the furnace and supported at their ends on side walls of the furnace, each of said beams consisting of a pair of inwardly facing channels connected in spaced relation by throughbolts at'their ends, laterally spaced rows of fire brick hangers of I-beam cross-section suspended from said beams ,with their upper flanges clamped between the beam channels, the hangers of each row being disposed in side to side con tact with each other, and flat flre brick slabs supported at opposite edges thereof on the lower flanges of said hangers, the slabs of each row being in edge to edgecontact with each other; said hangers being of suflicient depth to permit independent removal of said slabs from between their supporting hangers by a combined vertical and canting movement. 4

5. In combination with the structure defined in claim 1, layers of a powdered heat insulating material of higher insulating value than the hangers and slabs directly covering the slabs and the joints between the slabs and hangers, but out of contact with the beams.

6. In combination with the structure defined in claim 1, layers of diatomaceous earth overlying and in contact with the top surfaces of the slabs and in contact with the sides of the hangers and covering the joints between the slabs and hangers, but out of contact with the beams.

LESTER L. LADD. 

